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28X 


32X 


plaire 
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iques  du 
nt  modifier 
xiger  une 
de  filmage 


»d/ 
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taire 


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la  dernidre  page  qui  comporte  une  teiie 
empreinte. 

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dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbole  -^  signifie  "A  SUIVRE  ".  le 
symbole  V  signifie  "FIN  ". 

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iilustrent  la  m6thode. 


i  by  errata 
Imed  to 

ment 

.  une  pelure, 

)  fapon  d 

e. 


1 

2 

3 

32X 


1 

2 

3 

4 

5 

6 

I*. 


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From  the 


Proceedings  of  the  Anirvican  Associiitioii  for  tlic  Ailvaucemeul  ol  Science, 
rortliinil  Jleeliug,  August,  i'iT.i. 


On  the   Relations  of  the  Niagara  and  Lower  IIelp^rbero 

FOUMATIONS,     AND      THEIR     GeOCRAI'IIICAL     iJlSTHIMfriON     IN 

THE    United    States  and  Canada.      By  James'IIall,  of 

Albany,  N.  Y. 

In  proceeding  to  the  discussion  of  this  subject,  I  propose  in 

the  first  place  to  cite  a  paper  read  bj'  Mr.  A.  II.  Wortlieu  at  the 

Troy  Meeting  of  the  American  Association,  and  published  in  tlie 

Proceedings  under  the  following  title : 

'■'■  Itemarks  on  the  lidative  Aye  of  the  Niagara  and  so-called 
Lov:er  Helderberg  Oroups^  By  A.  II.  Worthen,  of  Sprhifjjield^ 
Illinois." 

"  Recent  investigations  have  developed  certain  facts,  bearing 
upon  the  question  of  the  relative  age  of  the  above  named  groups, 

(321) 


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v..      NAT!  1!.U.    HI-TOr.Y. 


'7 


wliicli  we  (li'-iro  to  iircsoiil  in  m  Inicf  iiiiiinu  r  fur  tlu'  coiisidoraliou 
of  thnsc  wlio  nrc  especially  iiileresleil  in  strntiiirnpiiieiil  ii'colojry.^ 

In  nnrtliern  iuul  weNteiii  Illinois.  I'loni  the  nioulii  of  llie  Ulinoi.s 
IJivLT  nortliwMiii  lo  tlie  Wiseonsin  line,  the  V\>\)cv  Silniiiin  divis- 
ion of  the  i);ilieo/.oie  series  is  represented  liy  l>nll',  gray,  ov  yellow- 
ish-urav  dolomites,  souiellnies  in  remarkably  oven  beds,  as  at 
Joliet,  and  (oatton;  and  at  other  localities  by  eoneretionary 
masses,  with  but  I'aint  traces  of  stratilicalion.  as  at  Ibidjicport, 
near  Chie:i<.n).  and  at  Tort  lUron  and  Leclare,  at  the  head  of  the 
Upper  Kapids  on  the  Mississippi  IJiver.  They  ran^io  in  thickness, 
from  seventy-live  to  three  hnndred  feet,  and  directly  overlie  tho 
fihales  and  arizillaceons  limestones  of  the  Cincinnati  uronp  of  the 
Lower  Silnrian  si'ries.  'I'hese  dolomites  are  (|iiite  fossil iferons, 
and  allbrd  many  iharacteristic  Xia;j,ara  species,  among  which  wo 
may  mention  J'l-iifKiiirrn.-i  (ililnniin^.  Spirij'cr  i-m^inlns,  ('(ihiiitviu; 
Jili'iiiiciib'tcliii,  Ciir'/iifi-iiDis  nnmhifi,  (JrllKffnin  u  mini  a  hi  m,  ete. 
From  the  I'ridLTcport  locality  alone,  nearly  oni'  hnndred  si^'cics  of 
fossils  have  been  ennmerated.  a  large  nnniber  of  which  are  specif- 
ically identical  with  those  found  in  the  Xiai:ara  bi'ds  of  New 
York  and  Canada;  and.  so  tar  as  we  are  aware,  all  Western  geol- 
ogists are  agreed  in  considering  these  dolomites  to  V)o  the  strati- 
"raphical  ei|uivalen1s  of  the  Xiagaia  group  of  New  York. 

In  southern  Illinois  we  tind  these  dolomites  replaced  i)y  a  series 
of  silicions  and  argillaceous  limestones,  forming  a  group  two 
hnmbed  and  lifty  feel  or  more  in  thickness,  which,  like  the  dolo- 
mites of  northern  Illinois,  rest  directly  \ipon  the  Cinoinniiti  group, 
and  are  immediately  succeeded  by  Devonian  strata.  At  the  base 
of  this  group  of  silicions  limestones  there  are  some  reddish  mot- 
tled bods,  from  ten  to  twenty  feet  in  thickness,  that  in  color  bear 
considerable  res<'ml)lanco  to  the  Medina  sandstone  of  New  York; 
and  these  mottled  limestones  pass  gradmdly  into  the  butf  and 
gray  silicions  beds  that  ccnistitute  the  upper  and  main  p(ntiou  of 
The  group.  Fossils  are  rare  in  the  lower  portion  of  the  group 
horel  but  the  mottled  limestones  contain  some  Orthnci'nitites, 
and  joints  of  large  CrinuidfiU  while  the  middle  and  ui)per  por- 
tions are  locally  (juile  fossiliferoiis,  and  have  atlbrded  many  of  the 
characteristic  siiecies  of  the  so-called  Lower  Ilelderberg  groui), 
among  which  are  the  following:  Or/his  siihrdrhintd.  (>.  oblatu, 
Cii-lns'pira  siihriiriiKita,  C.  imbricata,  Sj)iriJ'(rr  i^er-bnneHoi^iifi,  and 
ri((l>icc'ms  fipinile  of  Hall,  and  ^lrl<}(isii!>i  laimatus  of  Com-ad, 
together  with  species  closely  resembling,  if  not  identical  with, 
3l7'rista  prinrrjiK,  I'luliicerux'  p>jnniudalaia,  P.  unfjuljhnne,  P.  in- 
die, and  P.  muUixtriatum  of  Hall. 

In  the  first  volume  of  the  -Kcport  on  the  Geological  Survey  of 
Illinois,'  these  silicions  limestones  of  the  southern  portion  of  the 
state,  and  the  dolomites  of  northern  Illinois,  were  regarded  as 
tho  stratigrapliical  e(iuivalents  of  the  Niagara  group,  and  were  in- 
cluded together  as  representing  a  single  division  of  the  Upper 


*i 


1^ 


II.    xATiitAi,  ntsToin'.  •'-•' 

Silurian  scnics  ;  luit,  .nl.M.,,ii.'ntly.  in  a  corrcclo.l  section  ..f  Hi.' 
Illinois  stnitii.  iiMbiishcl  in  ihc  IntnMlnction  to  tlif  sccoiwl  \ni- 
unu"  wi-  were  indnrcK  IVoni  the  .lissiinihirily  of  llic  lo^ils  Ironi 
tlic  dilfcMTnt  sections  oi-  the  state,  to  rc-anl  the  silicions  Inne- 
stones  of  s,.nthcin  Illinois  as  the  representatives  ol  a  hiiih.T  '^m- 
lo<.-ical  horizon,  an.l  theivlore  |.iace.l  llieni  alx.ve  the  .lohnnites  ,, 
the  noithein  part  of  the  Stat.',  as  the  c,|nivalents  of  the  so-calU'. 
Lower  Uehl'Tl.ero-  oronp.  We  are  now.  however,  fnliy  sati>hi'cl 
from  .1  fnnlK'r  examination  of  tiiese  Ipper  Siiurnin  strata,  over  a 
more  extended  r.'uion.  that  our  lirst  c(uiclusion  was  correct,  and 
that  these  silicions  limestones  ;ind  dolomites  represenl  tne  .^anie 
..•,M.lo.d<'al  hori/on.  and  that  the  dillerence  in  the  sp.>cii:c  char- 
Mcler  of  their  fossil  cont.'nts  is  entirely  due  to  the  chanuvs  in  the 
oceanic  <.on.li;ions  under  which  they  were  deposited,  and  not  to 
the  dilferent  a"es  of  the  sediments  themselves. 

South  of  the  Ohio  iJiver.  t!ie>e  Tpper  Silurian  strata  are  lound 
well  exposed  in  'I\uness..e.  in  the  counties  of  Wayne.  I'eiry  and 
Decjijur.  on  the  'reunessec  Kiver.  outcroppin;i-  over  a  wide  area 
and  allbnlinL?  numerous  species  of  fossils  in  a  line  st:.le  ol  preser- 
vation. The  base  of  the  iiroup  here  consists  of  reddish  and  mot- 
tled limestones,  verv  similar  to  those  in  southern  Illinois,  and 
contain  Orlhnrrras  mubihilnm.  and  Joints  of  lar-e  crinoids  m  -ireat_ 
abundance.  These  red  limestones  are  sncceed.'d  by  a  series  .,1 
orecnish-.-niv  shales,  ami  slialy  ar-illaceous  limestones,  contain- 

mJni^  l'liHr">-«'<  Si'i<l<n-rus,-.  rmtoan-rNs  nl,lni,,i„s,  Orllns  h;lhriiUu 
0  ,-h"rn^tnh,,  etc.,  associated  with  siich  Lower  Ileldcrbei-i-  lorms 
■IS  ri'iit^imcnis  <i<i}<'„htx.  Splrifi-r  jU'r-litmcllnsns:  S.  „i,iri;,,,l,'>n;,. 
Mnrist<(  Id'ris.  ]{l,'i,i<'h<u„'lhi  reulriros».-<,  and  many  others,  showimz' 
that  the  fossils  of  these  so-called  >ir()Ui)s  are  lu'iv  iiitermin.-iln 
thromdi  the  same  strata,  conlirmin--  what  we  had  already  assumed 
to  be  true  in  Illinois,  that  the  Ipper  Silurian  beds  ol  the  U  c-t 
constitute  but  a  sinole  -iroup.  and  consc.iiiently  that  the  term 
Lower  Ilelderberu.  as  applied  to  a  -iroup  distinct  from  the  >iao- 
.ira,  is  supertlnons.  We  recollect  that,  on  visitin-  the  locality  o| 
these  so-called  Lower  Ilelderberp;  limestones  in  the  Schoharie 
vallev  some  years  aoo.  we  obseived  these  limestones  resting-  im- 
mediately upon  nud'isputed  Lower  Silurian  beds  there,  and,  in 
explanation  of  their  occnrronce  in  this  apiiarent  abnormal  posi- 
tion, we  were  told  that  the  Niagara  -roup  was  supposed  to  have 
thinned  out  to  the  eastward,  and  that  these  Lower  1  elderbeii;' 
limestones  took  tl'cir  place,  lint  is  it  not  .luite  as  probable  that 
there  has  only  b-en  a  change  in  the  litholo.uieal  chair-ter  ot  the 
beds  in  their' eastern  exteusi.)n  in  New  York.  resiillin«i-  there,  as 
in  Illinois,  in  a  decided  change  in  the  specilie  character  ol  the 
fossils  which  they  contain,  ami  that  the  Upper  Silurian  beds  at 
Schoharie  are  the  exact  eciuivalents  of  the  Niagar.i  shales  ami 
limestones  in  the  western  part  of  the  State .'' 


-ms^m-Es^PSPSnTT' 


„fj.i,i.jff3-r^--~Sm*i  ".-jJ<Sa»E»*» .  i-Mnfiini^"---id 


4 

.1 


:V.U 


II.      NATIKAl.    Il'STOItV. 


To  ruc'iipiliilato,  then,  tlic  iMcts  iis  they  arc  present ril  in  the 
"West;  wc  liiul  thnt  the  (hjU)iiiites  of  noitlierii  lUmois  contiun 
oiilv  Ni:i"-iini  fossils,  and  I  lie  silieioiis  liniestoiieH  of  the  soiitliern 
portion  o?  liie  StMte  eontiiin  onlv  tl-  >so  eoiisi(h'rea  ehiinietenstK', 
of  the  l.()>ver  llelderl.eru  -.nonp  ;  wliih"  tiie  l-eds  in  Tennessee, 
oecupyiiej;  tiiesanie  slnitiunipiii.-il  position  witii  tlie  (h)loinites  iuul 
llie  siiieiJns  limestones  of  Illinois.  Inive  Ni:i;iMi:i  iimi  J.ower  llel- 
,lcn>ei<''  fossils  interniinuled  iiidiseiimiiiiitely  thionjih  the  strata. 
Ileiiee'we  eoneln.le  that  the  so-ealled  Lower  Ilehlerherg  -rronp 
has  no  real  existence  as  a  distinet  ^n'onp  of  Upper  Silurian  strata, 
and  Ihu*.  <.he  iiai-.o,  hein.u  siiperlhiniis.  should  lie  dioi.ped  lioin  the 
iionieiielatiire  of  the  Ainerieaii  roeks." 

It  is  here  proposed,  in  an  article  oi"  less  Ih.an  th-'ee  pages,  to 
discard  entirely  from  the  jr(.ol.,oi(.;d  series  and  gcolo-rical  iioineii- 
clature  a  well  reeo-iiiized  j-roup  of  strata  :  well  Unown  a. id  clearly 
delined  for  more  than  one  iliousan<l  miles  in  extent  of  country, 
spreadiiii--  .liajioiially  over  nearly  or  (piite  lifleeii  de<;rees  of  lati- 
tude, while  its  undr.'ialiiiir  and  repeated  outcroi)s,  owing  to  anti- 
clinal erosion,  add  some  hundreds  of   miles   more  to  its  known 

(.'.\i)osure8. 

The  result  of  tedious  and  careful  /leld  investigations  in  the 
work.ng  out  of  hundreds  of  sections  in  various  parts  of  the  conn- 
try  iK.ve  been  suppleinente.l  hy  the  study  of  large  collections  cf 
niimevous  species  of  fossils,  and  the  linal  comparison  of  all  these 
foss'.ls,  from  the  far  northeast  or  the  St.  Lawrence  to  Tennessee 
0:1  the  southwest  —  from  tiie  IMississippi  valley  on  the  west,  from 
t'le  states  of  Iowa,  Illinois,  'A'isconsin,  the  Islands  of  Lake  Huron, 
and  Canada  West  (or  Ontario),  together  with  the  more  critical 
study  of  the  rocks  and  fossils  within  the  limits  of  the  state  of 
New  York —  are  all  to  he  set  aside,  and  a  simple  assertion,  un- 
supported by  sections,  by  fossils,  and  I  may  say  by  a  single  fact 
of  importance,  is  to  be  substituted  for  all  the  labors  of  thirty 

years. 

Thih-  assertion  comes  from  a  gentleman  holding  the  important 
and  responsible  position  of  State  Ceologist  of  Illinois,  whoso, 
name  is  associated  with  so  nnicli  of  the  geology  r  ad  paleontology 
of  the  West  as  to  give  currency,  if  not  authority  and  authenticity, 
to  what  he  may  say  :  —  and  certainly  he  ought  lot,  witiiont  good 
reason  and  authentic  data,  make  such  assertions  nor  put  such  a 
paper  before  the  American  Association  for  the  Advancement  of 

Science. 
liut  will  the  geologists  of  the  United  States  accept  this  so-called 


\ 


I 


n.    wniiM,  iiisroitv, 


825 


(Ictoriniiiation  of  tlic  iili'iitity  of  tlio  <iioiiiis  of  strMtji  known  iw 
llic  XiMiAUA  and  tlic  Lowi'.n  Hr.i.UKKiiKUd  ?* 

I'liil  Air.  Woillicn  is  not  oriiiinal  in  tliis  vi(  w  of  tin-  relations  of 
tlic  two  iiTonps  of  strata,  lie  lias  nu'iciy  icvivi"!  an  old  ami  tlis- 
canlcd  I'lTor.  Tlu'  same  .assertion  was  lony  .1;  o  niauc  in  tin-  (ii'o- 
logieal  IJcports  of  rennsylvani.n  and  else  viieic  ;  and  was  .at  oiu> 
time  tlie  <»iMUTaily  accepted  Itciici'  ainonu'  ui'olo.n'ists.  I'lol'essor 
IJo^iors,  in  a  pa|KM-  i;)on  Niagara  Fall-  piilili>lu'ii,  I  lifiiivc,  in 
is.".-.',  takes  tills  view  of  the  relations  o!  tlu'se  forinati(»ns,  ami  in- 
elndes  also  the  limestone  of  Ulaek  IJoek  nmler  the  same  desiii- 
nntion.  It  is  not  smprisln^  tliat  at  that  period,  when  no  eiitical 
pxaniinalions  had  leen  made,  when  we  Iiad  no  knowleiliic  of  |)ale- 
oiitolouT  as  a  iiiihle  In  the  more  oitsenre  .and  dilliiaill  poinl>.  that 
yrreat  snrfaee  features  should  have  lieeii  taken  as  jinides  in  the 
(lotcrminatlou  of  ucoloirieal  formations.  It  happened  in  thi-^  <'ase 
that  the  <i;reat  eseariiment  of  the  Niagara  at  Kewiston  ae.il  (^>ueens- 
town  was  reganled  as  the  e\teiis;,:i!  of  that  of  the  I  lelderlieri^ 
and  tho  south  sl(U>  of  llie  Moiiawk  valley.  'I'he  limestone  of 
Black  Ivoek.  though  so  far  sepaiated  from  Niagiua.  was  regarded 
as  a  part  of  the  same  :  the  features  in  iheWi'sl  ijeing  more  suh- 
dued,  as  was  supposecl. 

This  in  lirief  was  the  eondition  of  our  knowleclgc  and  lielief 
regarding  these  formations  at  the  lieginning  of  the  New  York 
Geological  Survey,  and  Co)'  some  time  afterward. 

Tlie  one  horiz(Mi  which  aliove  all  others  was  at  lliat  tinie  re- 
garded as  fixed  Iveyond  (piestion  was  that  (,il"  'he  salt-lieaiing 
strata.  This  formation,  at  its  base  hearing  .a  gre.at  thickness  of 
red  and  mottled  shales  and  marls,  succeeded  I>y  gray,  ash  or  drab 
coIohmI  hods  of  similar  dnractors.  and  limdly  hard  beds  of  linK!- 
fstono,  was  regarded  as  clearly  delined  Irom  Saltspringville  in  the 
iMohawk  valley,  hy  way  of  Syracuse,  .Montezuma,  anil  thence 
^vestward  along  the  base  of  the  Limestone  Terrace  from  Uoches'.cr 
to  Lowiston. 

Throughout  this  entire  extent  smU  springs  had  boon  discovered, 
and  brines  of  varying  and  <lillerent  (pialitie.s  were  known  to  exist. 
Ko  doubt  of  the  nature,  age.  or  identity  of  the  formation,  from. 

*01'  liito  years,  ill  cfitiiin  (lUiirtois.  it  lias  Ijccii  mily  lu'cosaiy  lo  cdMiadii't  "hat 
lias  bi'cii  (Imu'  in  llic  Slali;  iil'  New  \(irk.  or  by  iinsmis  in  lii'r  employ,  boUi  in  f;eo|of;y 
luiil  paleoiilolo^ry,  ti)  have  the  slaleiiieiit  aeee|ileil  on  liare  as>erlioii.  I  mifllit  iii>tan<e 
examples  too  numerous  (■)  lie  creditable  to  the  aeiinieii  ami  fiooil  sense,  to  say  iioihin^' 
of  the  scieiitille  ability,  or  those  who  pidiio>e  or  neccpt  such  conclusions. 


fr 


f 


f 


32G 


n. 


N.VTIWAI.    IlISTdUY. 


II.ikiiiHTroniily  I..  Ilic  \i;i-;un  liiv.TJit  Lcwistoii.  liinl  cvfr  liPOll 
,.Npiv.s..,l.  (,r.  s(.  r.'ir  MS  I  knew.  fnl.TtaiiiiMl  l.y  i.ny  one.  Now, 
tluMi-li  llii^  iiiiiy  seem  invli'vimt  t..  tlif  (|iifstinii  tu'lorc  us,  it 
ucvortli.'lcss  lies"  :it  tlic  lntiii.l:it  ion  of  tlif  I'lror  llicii  pivviiiciit, 
ictiMnlin-  til.'  Nin-niM  uiul  llrl,|..il.rr-  lonnMlioiis  ;  iind  is  iiiti- 
lUMtcly  roniu-i'tnl  witi.  tlic  -ivairr  cnnr  i..)w  soi.-iil  1..  Ik-  ivviw.l 
ill  liii'  piipiT  iimliT  (■uiisidiTiition. 

Jt  was  not  iiMtil  tlu'  dosi-  of  llu'  li.'i.l  w..ik  of  l^-^  tiiat  ll.is 
,,ursti(.n  came  \>vi\>vv  ilw  a-s,'iiii>|.',l  miciiiIkts  coiistitnlinM;  tin; 
(ominissicii  of  tiif  New  V..ik  ( Ifolonical  Survey.  Tlic  y...m-v>,t 
uwrnU'V  ..r  ll.al  Ixnly  iia.l  asMTlcd,  as  llu.  icsiiH  ..f  liis  iiivc-stig-a- 
ti,.i.s.  tliat  tlu'  rocks  at  tlir  ha>.'  ol'  tlu'  Ma^r:.,a  TciiaiN-,  coiisist- 
iiiii-  u{'  vi'i\,  -ray  and  inotll.Mi  marls  and  saiid^t  -„.'s,  w.tc  not  Uie 
(•(m!iiinati..n  oi"  tlic  salt  l.carinii'  lu-ls  of  Onondaga,  an.l  .■iM.wlicre 
to  tlic  eastward.  I.ut  a  lower  foniiatin,,  :  lliat  llie  Nia^^ara  lime- 
stone, so  lai.uely  .level. -lied  at  Nia-ara  an.l  L.-.^kpoil.  was  not  ii 
cmtinmitiou' of'  tlie  linu-stoiie  of  lla'  IleMeihero-.  l.iil  a  dislinet 
f..rination  :  liaviiij--  its  e;ivatesl  devel..iini.'nt  t..war.ls  tlie  west,  and 
oradnaliv  tliinniie^  to  the  eastwanl  :  an.l  that  inst.^a.l  of  lyiiifl 
ahove  the  Sail  loniKiti..n  it  lay  l.eneath  it  :  that  the  Salt  lovma- 
tion.  e\ien.liim-  westwanl  IVoiii  Syiaeiis.-.  passe.l  to  the  soiitliwanl 
of  th<-  Niagara  Terrace,  an.l  I'onue.l  the  lin.a.l  belt  of  Hat  eonntry 
to  the  south  o{  th."  raii-v.  wliieli  is  so  marke.l  a  feature  fr.)iii  the 
(u'uesec  Hivi'r  south  of  Uuchcsler  to  the  Xiauara  Wiver  at  Tone- 
wan.la  :  tiius  separatin;:-.  i.y  a  .listaiiee  of  several  miles,  the  lime- 
stone of  Niauara  and  that  of  Ulaek  Hock. 

Til.'  con.litions  which  ori-iiially  h'd  to  this  misapprehension  of 
the  relations  of  the  ditlerent  formations,  are,  the  flat  marshy  conn- 
try  from  the  outlets  of  S.-iieca  an.l  C'ayui-a  lakes  to  tin-  n.^rthward, 
Avhi.'h  has  obscured  the  outcn.ps.  and  beyond  this,  in  Wayne 
e.xinty.  the  -reat  a.vumulati.)!!  ..f  .Irift.  which  has  .leeply  eovered 
the  n'..'k  over  a  h:r-e  area.  If  to  tlu'se  we  add,  that  in  the  ear- 
lier iie..l.)i..ieal  explorations  th.'  line  of  the  Krie  canal  was  that 
principally  travellc.l.  —  that  the  passa.ire  from  the  rc.l  an.l  gray 
marls  of  th.'  Oiiomla-a  iv.^ion  t.)  the  red  an.l  mottled  marls  of 
the  Medina  San.lstone  at  H.n'hestcr  and  westward  of  the  CJeiiesec 
Hiver  was  thron-h  an  alluvial  or  .Irill  eonntry  which  concealed 
1h.'  nnilerlyinn-  ro.'k  lormations.  — the  supposed  identification  of 
th.'  two  formati.ms  is  not  sui'prisinij.-. 

That  such  views  shouM  i)rcvail  before  contimied  and  connected 


f 


f 


r 


i 


n,    NATi  i!Ai,  ni-ri>i!v.  •>-< 

()l)'^l•^V!lti^)n^  liMil  Iti'fii  ciuiii'.l  tin.  we  nn-  prciuirt'il  to  mnliTstMiiil  ; 
Imt  nlltT  iicfirlv  lorty  yoars  of  oliscrvntioii.  iiinl  mIIci'  IIic  ii'Im- 
tioiiH  of  ill!  tli('s(>  rock'*  liiivc  lu'cii  I'lilly  imdcrsioiMl  I'm'  thirty  vt'Mi's 
or  iiKMi'.  1  ^llllmit  tliiit  it  is  in>t  wurtliy  of  tlic  crcilit  of  tlir  Aiiicr- 
ic.'Ui  ANSoci;itioii  to  iillow  siicli  ;i  |p:iii('I'  to  psiss  into  its  pnlilicti- 
lions  wiliioiit  sciioiis  consiiliMiition.  I'crsoiiiilly  I  niiiy  lie  intcr- 
I'stcil  ill  this  ([lu'stion  iiioii'  tJKin  otiici's.  sincr  I  Iimvc  |inlili-iicii  :i 
voinnir  iiiinri|i:ii!y  iijion  tin-  |);ilcoiiloloL:y  ol"  lli>'  foiniMtioii  or 
jii'oiip  liiTc  proposed  ;u  he  (lisi':inlf(|  !is  liMvih'j;  no  scpiirati'  or  dis- 
lini't  existence  in  tiic  series;  lint  tlic  scienci'  of  i;'eolo;j:y.  find 
tlio^e  wild  pui>iie  tli.il  X'ielire.  lliive  Mli  inlei'e>l  ill  tliis  (|ilestioii 
f;ir  superior  to  cue  of  liu'ic  liersolKliity. 

(unlnijicill  i-rlillliiiis  Hull  ijc^ 'ij/'i  j'/i  irdi  ixicii.iidit  (if  Ihr  ijronpS  ill 
IlKI'fitiiill. 

StMilinu  from  llie  typieii!  loeidity  of  liie  \i;iL;:ir;i  uroiip.  where 
we  liJlve  of  tile  sli;de  and  limestone  ;i  tliielxliess  of  sometlliiej,'  more 
tli.'in  two  Imndred  feet,  .'ind  tmeiiej,  the  oiit(ro|)  in  an  easterly  direc- 
tion, we  lind  a  very  ;^radiial  Imt  pretty  constant  thiiininii'  <>f  the 
beds  of  the  formation,  so  that  at  a  point  one  iiniidred  miles  easl 
of  the  Niai^ara  IJiver,  it  has  a  thickness  of  scarcely  oii(>  Imiidreil 
feet.  l''ailher  cast .  in  Oneida  eoiiiity,  the  formation  is  still  thin- 
ner, and  in  >oiiie  places  lias  ]iec(jiiu'  in  \y.\\\  or  almost  entirely  :i 
l)recciate(l  and  concretionary  mass,  with  few  or  no  fos.sils.* 

(ioiim;  eastwanl  it  liecomes  still  fnither  atteimated.  Imt  can 
still  lie  traced  holh  in  its  physical  aspect  .'uid  outcrop,  ami  by  its 
fossil  conU'iits.  In  the  neij^hlioihood  of  Schoharie.  Cobleskill, 
C'herrv  valley,  etc  it  is  known  as  the  Coralline  ],iiiic>.tone.  from 
its  abiimlaiice  of  corals.  These  arc  principally  identical  with  tlio 
corals  of  the  Xiai^ara  liroiij)  in  western  Ni'w  Yoik  ;  and  most  of 
the  species  of  Ibachiopoda  which  occur  in  a  condition  to  be  recoff- 
ni/.eil.  are  similar  or  identical  witli  Niagara  forms,  while  there  aro 
several  species  quite  distinct  from  those  of  lli((  Niaji'iira  iiioiip  in 
the  west.  The  npi)er  limit  of  //(////s/V^'n  cuIciiiiIhIhs.  so  far  a.s 
known  in  Xew  York,  is  in  the  Niagara  limestone;  and  this  fossil 
occurs  ill  the  cornlline  liinestonc  at  Schoharie  and  at  I.itchlield  in 
Herkimer  tMMinty. 

1  have  given  in  vol.  ii,  I'al.  N.  Y..  p.  :121,  more  at  Icii'-tli  my 

*In  Hint  pint  (ir  llio  state  llic  Coiiniilioii  is  -.1  iii-ifrnillrMiil,  lliiil  it  \v;is  oi-iniiially  re- 
gavili'd  liy  Mr.  Vaiiiixi'in  iis  11  Mibiiriliiiiilu  incinbiT  d'  Ihc  I'luloiin  (ir  Clinti'ii  frnmii; 
mill  was  only  ici'ojjrni/.cil  Ijy  liim  !ih  a  distiiicl  IV  lalinii  in  ls;i!i;  al'td- tlie  iiivustiga- 
tiuii-  in  tlio  wo-tui'ii  counties  liad  sliown  its  Inie  ri'latious  ami  iiniioilani'e. 


^/ 


fr~ 


o 


886 


n.      NATt  ItAt.    llI'TOTtY. 


roaHoiis  for  roRMnlin<i  M-*  <'>ii.l  =n.-  limcHtonc  n«  the  cftstcrly  oon- 
timiuticii  of  til.'  Niiij-nm  -iroiip ;  aii.l  siiico  tlic  tiin.'  of  tlml  iniMi- 
cntioK,  T  liiivc  iiia.l."  niiiiu'i'oiis  ol.scrvatioiis  iipon  the  ivlMtiniis  <.f 
tlic  coialliii.'  lim(wt,.iic,  all  of  wliidi  have  ti'iidcil  to  coiilinii  tin- 
views  thm-  cxiMvsM'.l.  Tlii-.  cnialliiif  liiiu'stoiic  in  its  attenuated 
form  nm.v  l)e  ree(.fjjnize<l  in  tlu-  vall.-y  of  tlie  lindsun  Kiver  nii.ler- 
Ivinij  the  water-liuie  foiination  at  numerous  loealities. 

Now  retuinin^f  alon^^  this  line  of  onterop  to  the  Niafjam  Kiver, 
jind  roih)\vinu-  the  formation  to  tlu"  northwest,  we  llnd  it  expand- 
in;;  in  thieUnesH  and  aiva  thion-h  Canada  West  to  fai.ot'K  Head  ;^ 
aiU)earin^'  in  the  islands  alon,n  the  eastern  and  northern  side  of 
Lake  Huron,  an-l  stretching'  aeross  the  peninsula  IVom  St.  .lo-eph's 
Hiver  to  the  oiilhM  ..f  (ireen  Bay  ;  tlu-nee  oeeupyin--  th."  principal 
part  of  the  peninsula  l.ctwccn  ( ireen  Hay  and  i>alve  .Michifian,  it 
expands  to  tin'  soulhwanl  heyond  the  southern  limits  of  tliat  lake, 
and  thence  trends  to  the  we>t  and  northwol  liirouj-h  Illim)is  and 
I„wa.  From  the  Nia-iari'  IJivcr  westward,  the  formation  is  chietly 
a  maiinesian  limestone,  and  in  nuiny  loealities  carries  an  al.iin- 
dance  of  fossils;  liotli  the  physical  and  paleontologieid  evidence 
leave  no  donht  as  to  the  a^^v  and  relations  of  the  formation. 

Keturnin.Li  ajj;ain  to  the  eastward  and  southward,  we  find  that 
the  anticlinal  movement,  which  elevated  the  islands  in  the  weste.n 
part  of  Lake  F.rie.  has  Lronyht  up  the  Niagara  formation  in  llie 
udjaeent  parts  of  ( )hio,  where  it  is  nmrked  hy  thi>  iiresonce  of  a 
p;rcater  or  h-ss  proportion  of  its  characteristic  fossils.  Hero  it 
Htretches  in  a  h.w  axis  for  miles  to  the  south  of  the  lake,  and 
thence  s|)reads  and  outcrops  on  either  side  of  the  rocks  of  the 
Ilu.lson  lUver  and  Trenton  a.ue.  which  form  the  central  or  lower 
visible  portion  of  the  Cincinnati  axis, 

Followinij;  tliis  direction  it  extends  through  Kentucky  and  Ten- 
nessee, everywhere  carryini;  its  characteristic  fossils. 

Throuuliont  all  this  extent,  until  the  formaticm  reaches  Tennes- 
see, there  is  no  ([uestion  raised  as  to  the  identity  an<l  [.urity  of 
the'  Niaizara  iiioup.  Here,  it  is  said  that  the  fossils  of  the  Niag- 
ara are  iTiinLcU'd  with  those  of  the  Lower  Ilelderl.erg  uroup.  And 
a'j;ain,ou  tlie  Mississippi  River,  in  Illinois  and  Missouri,  we  are 
tJld  that  this  mingling-  of  the  fossils  of  the  two  periods  occurs. 

Bnt  before  proceeding  to  discuss  this  part  of  the  question,  let 
us  for  a  moment  give  attention  to  what  is  termed  the  Lower 
Helderberg  group  in  its  typical  localities. 


/J 


n.     NATlUAr,   IIISTOUY. 


n2!) 


>ily  con- 
it  imldi- 

itinlis  of 

linn  till! 
Icnimti'd 
■r  iiiuliT- 

•tt  llivor, 

I'XpMlul- 

'h  lli'iul ; 
11  s'kU'  of 
.lo-i'lili's 
iniiiciliiil 
■lii<i!Ui.  it 
liiil  lake, 
iiiois  and 
is  cliictly 
ill!  aliun- 
ovidcncc 
ion. 

liiid  tlial 
c  west  fill 
on  in  the 
I'licc  ot'  a 
Hero  it 
lak(>,  and 
ks  ()('  the 
or  lower 

and  Ten- 
's Tennos- 

imrity  of 

the  Niag- 
)np.  And 
iri,  we  are 

occurs, 
lestion,  let 
ihe  Lower 


/J 


Tn  the  Ilelderhovi  Mountains  in  AH-aiiy  oonnly,  and  in  Scho- 
harie aloii'i  the  valley  of  the  Schohari.'  Creek,  and  in  the  {'..l.leM-^ 
kill  valley,  we  lind  everywhere  a  scrirs  or  jironp  of  liniotnnes,  of 
which  w('.listinetly  reco},Miize  four  nienihers  ;  these  are  known,  in 
the  asc(  ndinii  order,  as  'rcntacnlite  limestone.  Lower  I'entaincnis 
limestone,  Shaly  limestone  and  Tpper  rentanierns  or  Scntella 
llmeHtone.  ■riicre  is  in  sum.-  places  for  miles  in  extent  a  mass 
of  Stromatop<.ra  limestone  hetwc.n  the  'rcntacnlite  ami  Lower 
I'cnfamcnis  |imest(.ncs.  ThcM.  L.-vtlicr con-litnte  the  Lower  Ilchl- 
cri.er;;  j>roup.  formiie,'  in  Alhany  county  the  has.- of  Ihe  Ilclder- 
ber},' mountains,  and  cxvrywhcre  succeeded  hy  the  Orisk.any  sand- 
Htom",  Canda-alli  and  Schoharie  nrjt  i.nd  Corniferons  limestone,^ 
and  these,  in  the  summits  of  the  hills  l.y  the  arenaceous  shales  of 
the  Iliimilton  uroiip. 

This  ^rronj)  of  limestones  is  everywiiere  characterized   l«y  the 
presence  of  fossils,  often  in  innncnsc  nnmhers.  and  spccilically, 
with  very  few  exceptions,  (piite   unlike   the  los>ils  of  the  ro.'ks 
above  or'l.elow  this  horizon.     I'roni  the  llcldcrhci-s,  and  tiic  val- 
ley of  the  Schoharie,  we  are  able  to  trace  the  formation  to  the 
westward  thron-h  ihe  northern  part  of  ( )tsc<;o,  and  the  southern 
part  of  Ucrkinier  and  Oneida   counties;    and,  accordin-;  to   Mr. 
Vaniixem,  it  is  recojiuized  in  the  eastem  part  of  Onondajia  coun- 
ty, by  the   presence  of  some  of  its   peculiar  fossils.     From   the 
Hehlerberii  mounlains  the  <;r,,up  orMdually  thins  to  the  westward; 
and  in  Herkimer  county  the  divisions  of  the  several  members  are 
scarcely  rcco<>nized.  the   entire  mass  becoming,'  more  completely 
calcareous  but  still  char<j;ed  with  an  abundance  of  the  character- 
istic fossils  of  the  group.     West  of  ( )nonda-a  county  the  i.lace  of 
tlie  formation  is  often  recognized  by  a  stratum  of  hard,  compact 
limestone  lying  beneath  the  ( )riskany  sandstone.*      It  is  .luite  evi- 
dent that  the  force  of  the  entire  groui)  diminishes  in  a  westerly 

direction. 

Keturning  to  the  point  of  departure  in  the  Ilelderbergs,  wo  arc 
able  to  tracH"  the  rocks  of  this  group,  in  their  clearly  defined  aud 
unmistakable  characters,  through  the  eastern  counties  of  Now 
York  to  t!ie  limits  of  the  state  of  New  Jersey.  In  the  north- 
west part  of  that  state  the  formation  has  been  distinctly  recog- 
nized  by   rrofessor  Cook.     The  same  has  been  fully  described 

*In  '^(.ine  fonm.,'  Ucimrts  on  tlie  (;..ol„Ky  of  Uk' wcston,  .•ountics.  tliis  rook  is  do- 
scribca  as  «oni  or  croauil  pruvious  to  tliu  aei>o.iliou  of  Ihu  Oribkaiiy  saiul-tone. 


A 


M^ 


\  \ 


I 


830 


15.      NATIltAI,    llISrOUY. 


as  tlio  "T.iniostono  foiiiiatioii,  No.  vi"  in  tlio  <;('f)l()gk'iil  siir\oy 
of  I'eiiiisvlviiiiia,  wlicrc  it  iiijpc'ars  in  nunii'iouN  outtTop.s,  and 
oxlcnds  tliencu  tlirougli  the  woslL'rn  part  of  ^Maryland  and  tlu'ongli 
Virii'inia,  alonu'  tiu'  Appalaciiian  rango  into  Tennossoi'. 

>»'()\vlicri'  tlirongiiont  tills  extent  of  country,  a.s  far  as  \'irgini!;, 
lias  any  one  sliown.  or  attempted  to  sliow,  tlie  mingling  of  lo\iei' 
Heidelberg  .•md  Niagara  forms  among  the  fossils.  In  the  large 
c(jl!ections  whieli  1  possess  from  Maryland  and  N'irginia.  I  have 
never  observed  the  least  evidence  of  such  mingling;  and  in  ^Mtny- 
laiid  and  the  adjacent  parts  t)f  >'iigiiiia  I  can  speak  from  i)i'rsonal 
olisi>r\ation  that  the  formation  is  as  well  di'liiied  physicall}-  as  in 
any  pait  of  New  Y(jrU. 

J-i't  ns  now  look  to  tiie  northeast,  wliere  the  geological  survey 
of  Canada  has  traced  the  lower  lielderberg  formation  from  ]\Ion- 
treal  to  (iaspe.  Having  examined  targe  collections  of  these 
l')ssils  from  the  (iasjie  region,  and  oUh'I's  from  \w.\x  Montreal, 
1  have  never  seen  the  least  indication  of  a  mingling  of  any  other 
forms  with  those  characteristic  of  the  lower  llelderbeig. 

"We  have  uow'  traced  this  formation  from  tiie  forty-third  par- 
allel in  the  state  of  New  York  to  about  the  thirty-lifth  parallel 
of  latitude  in  Ti'iinessec,  and  over  liie  greiiter  part  of  this  extent 
Ave  have  no  knowledge  of  a  mingling  of  the  fossils  of  the  two 
groups  or  formations.  Again,  from  the  vicinity  of  jMontr?al  to 
Gaspe,  a  distance  of  some  seven  hundred  miles,  the  formation 
■wherever  know,'  carries  its  characteristic  fossils. 

This  gi-ou))  is  likewise  recognized  in  the  state  of  Elaine,  where 
it  is  characterized  by  minierous  well  known  fossils  ;  and  it  is  not 
improbable  that  it  may  be  e(iually  so  in  the  eastern  townships  of 
Canada  anil  iu  the  belt  of  limestones  extending  through  \'ermont 
to  the  northern  part  of  IMassachnsetts. 

Having  thus  hastily  sketched  the  ground  occupied  by  these  two 
groups  of  strata,  wo  may  now  consider  their  relations  to  each 
other.  a\!d  the  evidence  of  the  mingling  of  the  fossils  which 
wonld  render  it  necessaiy  to  relieve  the  nomenclatnre  of  geology 
of  one  of  these  names,  heretofore  adopted,  and  in  general  use 
wlicrcver  geology  is  written  or  spoken. 

I  will  here  cite  a  single  sentence  from  the  paper  referred  to:  — 

"We  recollect  that,  on  Aisiting  the  locality  of  these  so-called 
lower  lielderberg  limestones  in  the  Schoharii'  valley  some  years  ago, 
Ave  observed  these  limestones  resting  immediately  upon  undisputed 


if 


\ 


>^ 


^-.a-i    ,<>-«.>.,.    . 


■MiMf  ««aM»  - 


n.      NATIi;.Vl.    1II>T(IKV. 


O  "I  1 


V 


>N 


!l 


luwcr  Siliirinu  IhmIs  IIutc  :  iiml.  in  cxiilMiiiitioii  of  tlicir  occiirroiirc 
1  tliis  iipiiiirt'Dt  !i1mi()1iii;i1  iiosilioii,  we  wcri'  toM  UkiI  tlic  Xiniiiiiii 
•Al'oill)    was   sil|")()>C(l   to   Ikivi'   tliilllUHl   out    to    tlic    f:i>t\v;U(l,    iUlil 
timt  tlu'sc  lov    •■  Ilcldcrlii'iii,-  liiiu'stdiics  took  tlii'if  i)l;ic('." 

Furtuiiatcly  or  iiiifortmiatcly  tlicrc  is  no  cviilciicc  i:ivi'!i  as  to 
the  aiitlioiity  or  ii.v  wliom  "  irr  n-m-  Inhl"  tliat  tl:o  Nia<iar!i  <ir,,iip 
liad  thimuMl  out  to  tlu'  eastward.  In  tiic  liisl  plac-c  lot  us  in(|uiro 
a^  to  tlu'  liR't  of  the  lower  lleiderberji'  ••limestones  nstinii:  inune- 
diately  npon  undisputed  lower  Silurian  lieds  tiiere"  or  elsewliere. 
Having;  lieen  laniiiiar  with  the  Selioharie  valley,  and  iiavino;  niaile 
numerous  seetions.  and  explored  lonu:  lines  of  outcrop  in  that 
valley,  in  the  lohleskill  valley  and  in  the  Ilelderlier^i'.  I  have 
never  been  ahle  to  see  the  lower  Ilehlerlierii'  limestones  resting 
npon  lower  Silurian  rocks.  On  the  contrary,  the  section  ol'  stiata 
everywhere  shown  is  the  following,  as  given  on  the  diagram,  from 
t!ie  sandstones  ol"  the  Hudson  IJiver  grouii  to  the  Ori-kauy  sand- 
stone : — 

Oriskany  sandstone. 

r  I'ppcr  I'eutanieius  limestone. 
Lower  Helderlierg  j    Shaly  limestone. 

\   Lower  rentamerus  limestone. 
}   Teiitaculito  limestone. 


group. 


AVater-linie  forination. 
Miagi'ra  gi'oup  =  Coralline  limestone. 


Lower  Silurian 


(ireen  shales  with  Iron  i)yrites. 
j  Sandstones  and   shales  of  the  Hudson 
(  River  group. 


Everywhere  the  lower  memlier  of  the  lower  Helderherg  gi'/up 
is  unmistakably  separated  from  the  sandstones  of  the  lower  ,'»i;ii- 
rian  a<>e  by  three  distinct  and  usually  well  nnirked  members  of 
till'  series. 

Tracing  the  lower  Hetderberg  formation  from  this  point  for 
sixty  uiiles  westward,  we  have  the  following  section  : — 


Oriskany  sandstone. 
Lower  Hclderberg  (*  Shaly  and  lower  I'eutamerus  limestones, 
group.  i  'reutacnlitc  limestone. 

*Tlio  luiiifv  l'ciitai)icni~  limestone  i^  not  ilcvL'ldiKMl  ;i>  a  Ui.-tiiK't  iiieiri1n.i-  uf  tlie 


groui). 


V 


332 


n.      NATinAL    IIISTOIiV. 


AVator-liuu'  fonnatioii. 
Onomlaji-ii  salt  uroup^Ked  uiid  gray  marls. 

Niaii'ara  <;-r<)iip=Coralliiio  liiiicstoiio. 

r  Gi'cfii  shales    and    sandstones  with    oalca- 
C'lint<Mi  gi'oiip:=  {  rt'ons   hands  i-ontaininy  inliTstraliliccl 

1  beds  of  rod  lumatitc. 

Medina  sandstone. 
Lower  Silurian  =  Ci  ray    and    bluish-gray   sandstones    and 

shales  of  the  Hudson  Rivor  group. 

Everywhere  the  lower  nuMnber  of  the  lower  Helderberg  group 
rests  upon  the  wat- r-linie  formation;  and  tue  latter  is  always 
present,  separating  the  former  from  the  coralline  or  Niagara 
limestone.  At  a  distance  less  than  one  hundred  miles  farther 
west,  in  a  line  from  Seneea  or  Ontario  to  Oswego  county,  we 
have  a  sectiwn  showing  the  following  formations ; — 

Oriskany  sandstone. 
Lower  Helderberg  group  (  Compact  grayish-bliio  limestones  in  a 
represented  by  {  band  of  a  few  feet  in  thickness. 

Water-lime  formation. 

Onondaga  salt  group  with  salt  springs 

and  gypsum  beds,  more  than  1,0(10 

feet  in  tiiickness. 
Niagara  group. 
Clinton  group. 
^Medina  sandstone. 
Hudson  Hiver  group. 

At  this  point  the  Niagara  group  is  separated  from  the  contin- 
uation of  the  lower  Helderl)erg  group  by  strata  of  more  than 
1,000  feet  in  thickness. 

Everywhere  throughout  New  York  the  lower  Helderberg  group 
is  underlaid  by  the  water-lime  formation  :  and  the  same  is  true  in 
New  Jersey,  rennsylvania,  Maryland  and  Virginia;  and  every- 
where throughout  New  York  and  Canada  West,  and  in  AVisconsiu 
and  Iowa  the  water-lime  fornuition  lies  above  the  Niagara  group, 


/\ 


•«<trp  ■»*:"*'? 


It.      NATIHAI-    IlISTOKY. 


333 


A 


or  its  rcpresontativo,  tlio  conilline  linu'slono.*  In  lu.  c:.so  .lo 
tlii'si-  two  lormiitions  come  toj^ellier  oxct'i-l  wlierc  llio  watoi'-liiue 
I'oniuition  is  iihscut. 

Certiiiiily  tiu-sc  InniKitions  aii"  widely  cnoii-ili  sci)nr:it('il  to  con- 
stitiite  (listiiu't  uroiips  over  tlie  areas  iiained. 

It  is  suggested  in  tl.e  l)ai)er  eite.l  tl.at  tlie  .lillerence  l.etween  tliu 
fossils  of  Ihe  lower  IleUlerherg  group  in  eastern  New  York,  and 
those  of  the  Niagara  groui)  in  the  central  and  westi'rn  part  of  tlio 
state,  is  due  to  "a  change  in  the  lithological  character  of  the  lieds 
in  their  eastern  extension." 

In  the  western   l)art  of  the  stale,  the  Niagara  group  is  com- 
posed of  calcareous  shales  and  dolomites.     The  lower  Ilelderl.erg 
group  in  the  eastern  part  of  the  state  consists,  in  its  lower  part, 
of  thick    and    thin   bedded  dark  or  black  limestones,  wilii  shaly 
partin.rs,  and  sometimes  with  thicker  intercalated  shaly  layers ;  to 
these  succeed  the  heavy  bedded  limestone  with  I'mtami'mx  <juU'a- 
tns,  which    by    the    intercalation    of  shaly    matter    becomes    tiiiu 
bedded,    and    passes    by    almost    insensible   gradations    into    the 
''  Shaly  Limestone,"  and  fmally  to  a  silico-calcareons  shah'-t     'l"li« 
hi.d.er  member,  in  many  localities,  is  the  thin  bedded  Upper  I'en- 
tamerns  limestone,  while  at  Becraft's  mountain  and  in  the  Ilelder- 
ber-    the    upper    member    is    a    heavy-bedded   encrinal    limestone 
soiiR'times  known  as  the  Scntella  limestone,  from  the  presence  of 
great  numl)ers  of  the  bases  of  A.-<i>idocn,tus.     The  shales  of  the 
Niagara  group  and  their  contained  bands  of  limestone,  which  are 
the  most^highly  fossiliferous  portion  of  the  group  in  New  York, 
are  not  dolomitic  ;  and  it  seems  a  most  extravagant  supposition, 
that  the  slight  lithological  ditferences  in  the  comi)osition  of  the 
strata  couhrproduce  an  entire  chumje  in  the  fauna  ;  presuming  the 
deposits  to  be  of  the  same  age. 

We  now  come  to  the  consideration  of  the  last  paragraph  of 
this  remarkable  paper,  in  which  we  have  the  following  summary  :— 

"To  recapitulate,  then,  the  facts  as  they  are  presented  in  the 
West-  we  fmd  that  the  dolomites  of  Northern  Illinois  contain  only 
Nia-rara  fossils,  and  the  siliceous  limestones  of  the  southern  i>or- 
tion"of  the  State,  oidy  those  considered  characteristic  of  the  lower 

*It  is  true  that  over  a  consMoinblo  part  of  tl.o  lake  r..>;ioi,,  llio  watci-li.ne  an,l 
Onoi.aaga  salt  g.-oup  have  been  crcU-l  Inm.  above  the  Niagara  lor,nalio„UH.,,la.e 
of  U.e.e  Borter  forn.ations  being  o..c,>„iea  by  the  lake..  See  Fo.ter  an.l  U  hUney'. 
Report  on  tlie  Lalie  Superior  I.anai)i>lri(t. 

tThe  phy-^ical  aspect  of  thi.s  portion  of  tlic  group  is  pro>scrvea  m  tlic  -siliceous 
Uinestoim'  of  this  age  in  the  southwest. 


334 


n.      XATintAL   Hlr^T'iKr, 


Ilt'ldorbprjr  firoiip  ;  wliilc  tlio  licils  in  'rciiiiossco.  occupyiiiij;  tlic 
Sivino  striitiLtrniiliical  i)()siti<ni  with  tlio  doldinitcs  mikI  tiic  siliccoiis 
liincstonos  of  Illinois,  liiuf  Niiifj;:ir;i  iind  lower  Ik'ldcrlicr.u  fossils 
minj^lcd  indiscriniiniiti'ly  tln'on<>li  tlie  stratii.  llont'c  wc  fonfltido 
timt'thc  so-enlU'd  lower  lloldertierji  lironp  luis  no  real  exisUnce 
as  a  dislinel  linnip  of  npiuT  Silurian  strata,  and  tliat  llie  name, 
boinji  snperllnuus,  slionld  lie  dropped  I'roui  tliu  nonienelatnri!  of 
the  American  rocks." 

The  valnc  of  this  conclusion  will  ho  best  appreciated  from  the 
fact  that  in  southern  Illinois  and  adjacent  parts  of  ^Missouri 
the  limestones  holdin>,f  the  characteri-^tic  Nia<iara  fossils  lie  be- 
neath those  containing  the  characteristic  lower  1  Ielderber<>- fossils  ; 
and  that  we  iwrcr  "have  Niagara  and  lower  Ilelderberg  fossils  in- 
discriminately mingled  through  the  strata  ;"  unless  it  be  in  the 
debris  along  the  outcrop  ;  and  I  assert  this  from  iny  own  obser- 
vation. The  same  is  true  of  the  beds  in  Tennessee;  and  though 
the  collections  of  I'ossils  made  on  the  outcrops  and  among  the 
debris  do  contain  fossils  of  the  Niagara  and  lower  Helderberg 
formations  mingled  together,  this  is  not  true  of  the  rocks  /(*  situ. 
In  this  opinion  I  do  not  rest  alone  ;  and  it  is  only  necessary  to 
consult  the  report  of  Professor  Salford  to  show  that  he  finds  both 
the  rocks  and  Ibssils  o."  the  lower  Helderberg  formation  distinctly 
separated  from,  and  lying  above,  those  of  the  Niagara  group. 

In  some  localities  Professor  Satlbrd  asserts  that  he  Ihids  fossils 
of  the  two  formations  mingling  along  the  line  of  contact,  which,  in 
the  absence  of  all  intervening  beds,  may  very  well  hai)pen.  And 
this  fact,  so  far  from  proving  the  identity  or  synchronism  of  the 
formations,  is  a  very  important  proof  of  their  distinction  in  order 

and  in  time.* 

In  reviewing  the  facts,  and  considering  the  known  range  and 
extent  of  the  Niagara  and  lower  Helderberg  g.onps.  their  close 
approximation  or  actual  contact  over  large  areas,  and  their  wide 
separation  in  other  places,  we  are  compelled  to  the  conclusion 
that  there  are  no  two  groups,  of  similar  comi)osition,  in  the  en- 
tire paheo/.oic  series,  which  are  so  clearly  distinct  and  which  can 
be  unmistakably  traced  over  so  wide  an  area  of  country,  both  in 
their  physical  and  lithological  character,  as  well  as  in  their  con- 
tained fossils. 

That   there   are  designations   among   some   of  the  formations 

♦Wem.ayliKiuli-ealsowlieUicr  it  may  not  be  infoneil  tliat  tlio  living  organisms  of 
tlio  lower  IleUlin-berg  poriod  were  s-pread  over  a  sea  bottom  covered  with  llie  dead 
organisms  of  the  preceding  period  and  became  mingled  m  this  manner. 


-."Si^iS^ 


\vin<2;  the 
siliccods 
I'o-  fossils 

t'OIlfltlllo 

oxisUiice 
Jic  iKiiiie. 
ilatiire  (jf 


from  Uic 
jMissoui'i 
lis  lie  l)e- 
•<>■  fossils ; 
fossils  ill- 
lie  ill  the 
kvii  ol)ser- 
1(1  though 
iiioiig  the 
ielderbei'g 
ks  ('((  sifit. 
pcssiiry  to 
iiids  both 
distinctly 
roup, 
ids  fossils 
which,  ill 
len.  And 
sm  of  the 
n  in  order 


fi\ 


\ 


B.      NATIUAL    lIIsrOUY. 


Which  are  superflnons,   we  are  willing  to  admit  ;    hut  the  i-ropo 


sition  to  drop  from  the  system  one 


the  most  widely  distrildited 


formations  of  the  country,  whos.-  geological  position  and  ivlatioiis, 
and  the  fossil  contents  of  which  aiv  so  well  known,  is  scarce.y 
the  i)roper  mode  of  improving  -the  n.nueiiclature  of  the  Amer- 
ican rocks." 


[I'nutfd  iit  tlie  s.vi.KM  I'ui:»s.  .Iiuic.  18Tt. 


range  and 
heir  close 
their  wide 
conclusion 
ill  the  eii- 
which  can 
•y,  both  in 
their  con- 

ronnations 

orgnnisras  of 
vith  tlie  deuil 


i 


r 


r.i 


^.. 


